Tissue removal device for neurosurgical and spinal surgery applications

ABSTRACT

A tissue cutting device that is especially suited for neurosurgical applications is disclosed and described. The device includes a handpiece and an outer cannula in which a reciprocating inner cannula is disposed. The inner cannula includes a hinge between a body section and a cutting section that allows the cutting section to pivot when the inner cannula reciprocates within the outer cannula. A tissue collector is also provided and is in fluid communication with the lumen of the inner cannula. The outer and inner cannulae are offset from the motor and drive assembly, and the center of gravity of the device is in the forward part of the device, providing an ergonomic design that is particularly suited for neurosurgical applications.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.12/391,579, filed on Feb. 24, 2009, which is a continuation-in-part ofU.S. application Ser. No. 12/389,447, filed on Feb. 20, 2009, which is acontinuation-in-part of U.S. application Ser. No. 12/336,054, filed Dec.16, 2008 and U.S. application Ser. No. 12/336,086, filed Dec. 16, 2008,each of which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to tissue cutting devices, in particular,tissue cutting devices that are suited for neurosurgical and spinalsurgical procedures.

BACKGROUND

Various abnormalities of the neurological system, such as brain andspinal tumors, cysts, lesions, or neural hematomas, can cause severehealth risks to patients afflicted by them, including deterioration inmotor skills, nausea or vomiting, memory or communication problems,behavioral changes, headaches, or seizures. In certain cases, resectionof abnormal tissue masses is required. However, given the complexity andimportance of the neurological system, such neurosurgical procedures areextremely delicate and must be executed with great precision and care.Many known tissue cutting devices suffer from an inability to quicklyand cleanly sever neurological tissue samples without causing “traction”or pull on the surrounding tissue. In addition, many known devices arenot configured to both “debulk” large structures and to finely shavesmaller, more delicate structures and lack the flexibility needed inmany procedures. Furthermore, many neurological procedures imposesignificant space limitations on the surgeon, and the tissue resectiondevice needs to be manipulable by the surgeon with one hand inrelatively small spaces. Many known devices either emulsify the resectedtissue, macerate the resected tissue, or thermally damage the tissuerendering it unsuitable for subsequent analysis (e.g., pathologic and/orhistologic analysis) which is necessary for the determination of themost effective post resection treatment therapies. Thus, a need hasarisen for a tissue cutting device that addresses the foregoing issues.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present disclosure will now be described by way ofexample in greater detail with reference to the attached figures, inwhich:

FIG. 1 is a perspective view of a tissue cutting device in accordancewith a first embodiment;

FIG. 2 is a cross-sectional view of the tissue cutting device of FIG. 1depicting an inner cannula in a first relative position with respect toan outer cannula in which the inner cannula's distal end is locatedproximally of the outer cannula's distal end;

FIG. 3 is a cross-sectional view of the tissue cutting device of FIG. 1depicting the inner cannula in a second relative position with respectto the outer cannula in which the inner cannula's distal end is locatedat the distal end of the outer cannula;

FIG. 4 is a partial cross-sectional view of the tissue cutting device ofFIG. 1 in a first configuration in which a device-mounted tissuecollector is disconnected from a tissue cutting device housing;

FIG. 5 is a partial cross-sectional view of the tissue cutting device ofFIG. 4 in a second configuration in which the device-mounted tissuecollector is connected to the tissue cutting device housing;

FIG. 6 is a partial cross-sectional view of an alternate embodiment ofthe tissue cutting device of FIG. 1 in a first configuration in whichthe device-mounted tissue collector is disconnected from the tissuecutting device;

FIG. 7 is partial cross-sectional view of the tissue cutting device ofFIG. 6 in a second configuration in which the device-mounted tissuecollector is connected to the tissue cutting device;

FIG. 8 is a broken side elevation view of the outer cannula of thetissue cutting device of FIG. 1;

FIG. 9 is a broken side elevation view of the inner cannula of thetissue cutting device of FIG. 1;

FIG. 10 is a top plan view of a portion of the outer cannula of thetissue cutting device of FIG. 1 with the inner cannula removed from theouter cannula;

FIG. 11 is a top plan view of a portion of the inner cannula of thetissue cutting device of FIG. 1;

FIG. 12 is a top plan view of a portion of the outer cannula and innercannula of FIG. 1 depicting the inner cannula inserted into the outercannula;

FIG. 13 is a partial cross-sectional view of a distal region of theouter cannula and the inner cannula of the tissue cutting device of FIG.1, depicting the inner cannula in a first relative position with respectto the outer cannula;

FIG. 14 is a partial cross-sectional view of a distal region of theouter cannula and the inner cannula of the tissue cutting device of FIG.1, depicting the inner cannula in a second relative position withrespect to the outer cannula;

FIG. 15 is an exploded assembly view of the tissue cutting device ofFIG. 1;

FIG. 16 a is a side elevation view of a cam of the tissue cutting deviceof FIG. 1;

FIG. 16 b is an end elevation view of the cam of FIG. 16 a;

FIG. 17 a is a perspective view of a cam transfer mechanism of thetissue cutting device of FIG. 1;

FIG. 17 b is a perspective view of a cam follower of the tissue cuttingdevice of FIG. 1;

FIG. 18 is a partial perspective view of a portion of the tissue cuttingdevice of FIG. 1 with an upper shell of an outer sleeve upper housingremoved to show a dial for rotating the outer cannula;

FIG. 19 is a partial side cross-sectional view of the portion of thetissue cutting device of FIG. 18;

FIG. 20 is a side elevation view of an inner and outer cannula assemblyof the tissue cutting device of FIG. 1;

FIG. 21A is a tissue cutting system including a remote tissue collector,control console, foot pedal, and the tissue cutting device of FIG. 1;

FIG. 21B is an enlarged view of the remote tissue collector of FIG. 21A;

FIG. 22 is a block diagram of a control scheme for the tissue cuttingsystem of FIG. 21A;

FIG. 23 is diagram of the tissue cutting device of FIG. 1 and the motorcontrol unit of FIG. 22;

FIG. 24 is a partial cross-sectional view of the tissue cutting deviceof FIG. 1 depicting motor shaft position sensors for controlling a stopposition of an inner cannula;

FIG. 25 is a partial cross-sectional view of the outer cannula and innercannula of the tissue cutting device of FIG. 1 with the inner cannula ina first position relative to the outer cannula;

FIG. 26 is a partial cross-sectional view of the outer cannula and innercannula of the tissue cutting device of FIG. 1 with the inner cannula ina second position relative to the outer cannula;

FIG. 27 is a partial cross-sectional view of the outer cannula and theinner cannula of the tissue cutting device of FIG. 1 with the innercannula in a third position relative to the outer cannula;

FIG. 28 is a rear elevational view of the tissue cutting device of FIG.1;

FIG. 29A is a perspective view of a single hand gripping the tissuecutting device of FIG. 1 in a first gripping position;

FIG. 29B is a perspective view of a single hand gripping the tissuecutting device of FIG. 1 in a second gripping position;

FIG. 29C is a perspective view of a single hand gripping the tissuecutting device of FIG. 1 in a third gripping position

FIG. 30 is a side elevational view of an embodiment of an endoscope foruse with the tissue cutting device of FIG. 1;

FIG. 31A is a side elevational view of an embodiment of a trocar for usewith the endoscope of FIG. 30 and the tissue cutting device of FIG. 1;

FIG. 31B is a detail view of the distal tip of the trocar of FIG. 31A;

FIG. 32 is a side elevational view of an embodiment of a tissue imagingand cutting device;

FIG. 33A is a depiction of a surgeon performing an open craniotomy usinga microscope and the tissue cutting device of FIG. 1;

FIG. 33B is a detail view of a portion of FIG. 31A;

FIG. 34A is a depiction of a surgeon performing an open craniotomy usingan endoscope and the tissue cutting device of FIG. 1; and

FIG. 34B is a detail view of a portion of FIG. 32A.

DETAILED DESCRIPTION

Referring now to the discussion that follows and also to the drawings,illustrative approaches to the disclosed systems and methods are shownin detail. Although the drawings represent some possible approaches, thedrawings are not necessarily to scale and certain features may beexaggerated, removed, or partially sectioned to better illustrate andexplain the present disclosure. Further, the descriptions set forthherein are not intended to be exhaustive or otherwise limit or restrictthe claims to the precise forms and configurations shown in the drawingsand disclosed in the following detailed description.

Described herein are tissue cutting devices that are suited forneurosurgical applications such as the removal of spine and braintissue. The devices are configured with a “gun sight” design in whichthe axis of tissue cutting is spaced apart from a motor drive and driveassembly housing. The gun sight design provides a shorter device that isparticularly well suited for many space-limited neurosurgicalprocedures.

Referring to FIG. 1, a tissue cutting device 40 includes a handpiece 42and an outer cannula 44. In one exemplary configuration, handpiece 42 isgenerally cylindrical in shape and is preferably sized and shaped to begrasped with a single hand. Handpiece 42 includes a lower housing 50which comprises a proximal section 46 and distal section 48. Lowerhousing 50 has a longitudinal axis L₁ extending along its lengthwisedirection. In addition, lower housing 50 has a middle point MP that ismid-way (FIGS. 2 and 3) between its proximal and distal ends.

Lower housing 50 comprises a proximal-most housing portion 82 (FIGS. 2and 3) that is connected to a motor housing 71, and a cam housing 69that is connected to motor housing 71. A front housing section 55 isconnected to cam housing 69. Upper housing 52 is also provided. Upperhousing 52 is connected to the lower housing 50 and is spaced apart fromlower housing longitudinal axis L₁ in a direction that is perpendicularto L₁. In the example of FIGS. 2 and 3, upper housing 52 is locateddistally of the lower housing midpoint MP in the direction along thelongitudinal axis L₁. A tissue collector 58 may be operatively connectedto upper housing 52 (as will be explained in further detail below). Arotation dial 60 for rotating the outer cannula 44 with respect tohandpiece 42 is also mounted to upper housing 52. Upper housing 52 is agenerally elongated structure extending along a portion of the length oflower housing 50 and has a longitudinal axis L₂ which is spaced apartfrom and substantially parallel to lower housing axis L₁.

As best seen in FIGS. 2, 3, and 20, outer cannula 44 includes an openproximal end 45, a closed distal end 47, and a distal opening 49proximate distal end 47. Outer cannula 44 is partially disposed in upperhousing 52 and projects distally away from upper housing 52 in thedirection of upper housing longitudinal axis L₂. Tissue cutting device40 further comprises an inner cannula 76 which is partially disposed inan outer cannula lumen 110. Inner cannula 76 is configured toreciprocate within outer cannula lumen 110 (FIG. 8) and to cut tissuesamples entering outer cannula 44 via outer cannula distal opening 49,as will be described in greater detail below. Inner cannula 76 extendsalong the longitudinal axis L₂ of the upper housing. In the example ofFIGS. 2 and 3, inner cannula 76 is coaxial with upper housinglongitudinal axis L₂. Inner cannula 76 reciprocates between a proximalposition, which is depicted in FIG. 2, and a distal position which isdepicted in FIG. 3. Inner cannula 76 includes an open proximal end 77and an open distal end 79. Distal end 79 is preferably configured to cuttissue, and in preferred embodiments is capable of cutting neurologicalsystem tissues such as those from the brain or spine. In one exemplaryembodiment, inner cannula distal end 79 is beveled in a radially inwarddirection to create a sharp circular tip and facilitate tissue cutting.

Outer cannula 44 is not translatable, and its position with respect tohandpiece 42 along the direction of the longitudinal axes L₁ and L₂remains fixed. Motor 62 is disposed in proximal lower housing section 46of handpiece 42 and is operably connected to inner cannula 76 to drivethe reciprocation of inner cannula 76 within outer cannula lumen 110(FIG. 8). Motor 62 may be a reciprocating or rotary motor. In addition,it may be electric or hydraulic. However, in the embodiment of FIGS. 2and 3, motor 62 is a rotary motor, the rotation of which causes innercannula 76 to reciprocate within outer cannula lumen 110.

Motor 62 is housed in motor housing 71, which defines a portion of lowerhousing proximal section 46. Motor 62 is connected to an inner cannuladrive assembly 63 (not separately shown in the figures) which is used toconvert the rotational motion of motor 62 into the translational motionof inner cannula 76. At its proximal end, motor housing 71 is connectedto proximal-most housing portion 82, which includes a power cable port84 and a hose connector 43, which in the exemplary embodiment of FIG. 3is an eyelet. Hose connector 43 provides a means of securely retaining avacuum system hose to handpiece 42, thereby allowing vacuum to besupplied to tissue collector 58.

Inner cannula drive assembly 63 comprises a cam 64, a cam follower 68, acam transfer 72, and a cannula transfer 74. As best seen in FIGS. 2 and3, drive assembly 63 is spaced apart from upper housing 52, innercannula 76, and outer cannula 44 in a direction that is substantiallyperpendicular to upper housing longitudinal axis L₂. By configuringdevice 40 with the cannulae 44 and 75 offset from lower housing 50 inthis manner, the overall length of device 40 is reduced relative to thelength of a fully “in-line” device in which the cannulae 44 and 76 areco-axially aligned with the drive assembly 63. The reduction in lengthprovides a device 40 that is particularly well-suited for use inspace-limited surgical procedures, such as many neurosurgicalprocedures.

In one illustrative example, device 40 has a weight distribution alongthe longitudinal axis L₁ such that the amount of weight between motor 62and the proximal end 77 of inner cannula is greater than the amount ofweight in motor housing 71 or distally of inner cannula proximal end 77along the direction of axis L₁. In another example, device 40 has acenter of gravity that is located distally of lower housing mid-pointMP, and which his more preferably also proximal of inner cannulaproximal end 77. The concentration of the device weight in the middleregion of the device (i.e., between the proximal and distal ends)provides for a more ergonomic balance of the instrument which reducesuser fatigue, allows for more accurate placement of the device during aprocedure as well as more control over the device when it is requiredfor more delicate and precise aspects of the procedure, such as whenshaving tissue next to delicate or critical structures. The capabilityto have a device that is easier to handle and provides for a morebalanced instrument reduces the amount concentration/focus and energyrequired from the surgeon and enables the surgeon to remove more tissuesafely than prior art instrumentation, particularly when the device isused in a single-hand grip procedure.

In addition, in one exemplary configuration, drive assembly 63 islocated distally of lower housing midpoint MP such that it is disposedbetween the midpoint MP and the distal end of the lower housing 50.Drive assembly 63 is also positioned between the lower housing midpoingMP and the portion of outer cannula 44 that projects distally away fromupper housing 52 with respect to the direction along the longitudinalaxis L₁. In the example of FIGS. 2 and 3, drive assembly 63 is alsolocated proximally of the proximal end 45 (best seen in FIG. 20) ofouter cannula 44 such that drive assembly 63 is positioned betweenproximal outer cannula end 45 and lower housing midpoint MP along thedirection of longitudinal axis L₁.

Cam 64 is a generally cylindrical structure and is shown in detail inFIGS. 16A and 16B. A groove or channel 65 is defined in the surface ofcam 64. In one exemplary embodiment, groove 65 is continuous andcircumscribes the perimeter of cam 64 but is not orientedperpendicularly to the longitudinal axis of cam 64, i.e., groove 65 isangled with respect to the cam axis. Opposing points on groove 65 suchas points 65 a and 65 b (FIGS. 2 and 3) define pairs of “apexes” thatare spaced apart along the longitudinal axis of the cam, i.e., thegroove extends along a portion of the length of the cam. Cam 64 alsoincludes a proximal opening 114 (FIG. 16 a) for receiving a motor shaftand a proximal recess 116 into which a shaft may be snugly received.Holes 118 and 120 (FIGS. 16 a and 16 b) are provided for mounting camrotational position indicators 176 a and 176 b that cooperate with aposition sensor to determine the angular position of cam 64, andcorrespondingly, the linear position of inner cannula 76 within theouter cannula lumen 110, as discussed below.

Cam follower 68 is depicted in detail in FIG. 17B. Cam follower 68 is agenerally rectangular block shaped structure with a hollow interior inwhich cam 64 is partially disposed. Cam follower 68 also includes a hole70 in its upper face in which a ball bearing (not shown) is seated. Theball bearing rides in cam groove 65 and engages cam transfer 72. As aresult, when cam 64 rotates about lower housing longitudinal axis L₁,cam follower 68 translates along the length of handpiece 42 in thedirection of L₁. Cam follower 68 also includes lateral slots 182 a and182 b that cooperatively engage corresponding members 178 a, 178 b fromcam transfer 72.

Cam follower 68 is disposed within a cam chamber 67 formed in camhousing 69 and is located distally of lower housing midpoint MP. Cam 64is partially disposed in cam chamber 67 (FIGS. 2 and 3) and extendsproximally therefrom to engage motor 62. Cam housing 69 comprises partof distal housing section 48 of handpiece 42. Cam 64 does notreciprocate within cam chamber 67 and instead merely rotates about itsown longitudinal axis L₁. However, cam follower 68 reciprocates withincam chamber 67 along the direction of the longitudinal axis L₁. Camfollower 68 is open at its proximal end to receive cam 64. As shown inFIGS. 15 and 16A, cam 64 may optionally include a threaded distal end123 that projects through a distal opening 191 (FIG. 17 b) in camfollower 68 and which engages a nut 190 (FIG. 15) to preventreciprocation of cam 64 relative to cam housing 69. Proximal cam bearing186 and distal cam bearing 188 (FIG. 15) may also be provided to supportcam 64 as it rotates within cam housing 69.

Cam transfer 72 extends from cam chamber 67 into a cam transfer chamber73 formed in upper housing 52. As best seen in FIG. 17 a, cam transfer72 comprises a proximal end 72 a that is attachable to cam follower 68and a distal end 72 b that is attachable to inner cannula 76 via cannulatransfer 74. Proximal end 72 a comprises a pair of spaced apart,downwardly extending members 178 a and 178 b, and distal end 72 bcomprises a pair of spaced apart upwardly extending members 180 a and180 b. Downwardly extending members 178 a and 178 b are spaced apart ina direction that is perpendicular to lower housing longitudinal axis L₁,the length of cam 64, and handpiece 42, while upwardly extending members180 a and 180 b are spaced apart in a direction that is parallel to thelength of cam 64 and handpiece 42. Cam follower slots 182 a and 182 bengage downwardly extending members 178 a and 178 b of cam transfer 72.Downwardly extending members 178 a and 178 b of cam transfer 72 may beresilient and may have engagement portions 179 a and 179 b on their freeends (e.g., hooks or clips) for securely engaging the bottom and sidesurfaces of cam follower 68.

As best seen in FIG. 20, cannula transfer 74 comprises a sleeve disposedabout inner cannula 76. Cannula transfer 74 comprises a proximal end128, middle section 127, and distal end 126. Upwardly extending members180 a and 180 b of cam transfer 72 (FIG. 17A) define fork-shapedstructures that receive and cradle middle section 127 of cannulatransfer 74. Distal end 126 and proximal end 128 of cannula transfer 74are disposed outwardly of upwardly extending members 180 a and 180 b andare shaped to prevent relative translation between cam transfer 72 andcannula transfer 74. In the depicted embodiments, distal end 126 andproximal end 128 of cannula transfer 74 are enlarged relative to middlesection 127 to abut the upwardly extending, fork-shaped members 182 aand 182 b, thereby preventing relative translation between cam transfer72 and cannula transfer 74. As a result, when cam transfer 72reciprocates along the direction of lower housing longitudinal axis L₁,cannula transfer 74 reciprocates as well. Because it is affixed to innercannula 76, when cannula transfer 74 reciprocates, it causes innercannula 76 to reciprocate within outer cannula 44 along the direction ofupper housing longitudinal axis L₂.

In one exemplary arrangement, motor 62 is a brushed DC motor and may beoperably connected to cam 64 in a number of ways. In the embodiment ofFIGS. 2 and 3, motor 62 includes a distally extending shaft 66 thatextends into a proximal opening 114 and engages recess 116 defined incam 64 (FIG. 16A). Shaft 66 may be connected to cam 64 via a threadedconnection, adhesive, or other known connection means. In an alternateimplementation, depicted in FIG. 15, a separate cam coupler 184 isprovided. Cam coupler 184 is seated in proximal opening 114 and has awidth greater than the diameter of opening 114. Cam coupler 184 is alsoconnected to motor shaft 66 such that rotation of shaft 66 causes camcoupler 184 to rotate, which in turn causes cam 64 to rotate therewith.One revolution of motor shaft 66 causes cam 64 to rotate by onerevolution, which in turn causes inner cannula 76 to reciprocate by onecomplete stroke, i.e., from the position of FIG. 2 to the position ofFIG. 3 and back to the position of FIG. 2.

Cam transfer 72 may be connected to cam follower 68 by mechanical means,adhesive means or other known connection means. In one exemplaryembodiment, downwardly extending members 178 a and 178 b mechanicallyclip onto and removably engage cam follower 68. In another embodiment,cam transfer 72 is adhesively affixed to cam follower 68. In yet anotherembodiment, both mechanical and adhesive connections are used. The ballbearing (not shown) disposed in cam follower hole 70 traverses camgroove 65 as cam 64 rotates, causing cam follower 68 to reciprocate fromthe proximal position of FIG. 2 to the distal position of FIG. 3. As aresult, cam transfer 72, cannula transfer 74 and inner cannula 76translate between their respective proximal positions of FIG. 2 andtheir respective distal positions of FIG. 3 when motor 62 and cam 64rotate. In certain examples (not separately shown), motor 62 may beconnected to a cam follower, and the cam follower may be connected to acam which is in turn operatively connected to the inner cannula. Inaccordance with these examples, when the motor rotates, the cam followerrotates and causes the cam to reciprocate, thereby causing the innercannula to reciprocate.

Motor 62 is preferably selected to have a rotational speed that allowsinner cannula 76 to reciprocate from the position of FIG. 2 to theposition of FIG. 3 and back to the position of FIG. 2 at a rate of atleast about 1,000 reciprocations/minute. Reciprocation rates of at leastabout 1,200 reciprocations/minute are more preferred, and reciprocationrates of at least about 1,500 reciprocations/minute are even morepreferred. Reciprocation rates of less than about 2,500reciprocations/minute are preferred. Reciprocation rates of less thanabout 2,000 are more preferred, and reciprocation rates of less thanabout 1,800 reciprocations/minute are even more preferred. As best seenin FIG. 14, the rates of reciprocation of device 40 allow tissue to besevered into “snippets” 112 which are relatively smaller than “slug”tissue samples obtained by many prior devices. As the reciprocationcontinues, a continuum of severed tissue snippets 112 is obtained.

As mentioned previously, outer cannula 44 includes an opening 49 forreceiving tissue into outer cannula lumen 110. As best seen in FIGS.8-12, opening 49 is preferably defined by a cutting edge 51 that isconfigured to sever tissue and a non-cutting edge 53 that is notconfigured to sever tissue. In certain exemplary implementations,non-cutting edge 53 has a radial depth “d” that is no greater than about50% of the outer diameter of outer cannula 44. In one exemplaryimplementation, cutting edge 51 is beveled in a radially inwarddirection, non-cutting edge 53 is not beveled, and cutting edge 51 islocated immediately distally of non-cutting edge 53. Inner cannuladistal end 79 is preferably configured to cut tissue. In one exemplaryembodiment, distal end 79 is beveled in a radially inward directionaround the circumference of inner cannula 76 to provide a sharp edge. Astissue is received in outer cannula opening 49, it is compressed betweeninner cannula distal end 79 and outer cannula cutting edge 51, causingthe received tissue to be severed from the surrounding tissue.

Tissue cutting device 40 is particularly well suited for use in cuttingtough tissues such as spinal and brain tissues. Outer cannula 44 andinner cannula 76 comprise materials that are generally rigid, such asrigid plastics or metal. In one preferred implementation, both cannulaecomprise stainless steel, and more preferably, 304SS typically used inmedical grade instruments.

As best seen in FIGS. 9-13, to facilitate the cutting of tough tissues,inner cannula 76 includes a hinge 80. Hinge 80 is located between innercannula body section 81 which is located on the proximal side of hinge80 and inner cannula cutting section 83 which is located on the distalside of hinge 80. In one exemplary arrangement, hinge 80 is a livinghinge. As used herein, the term “living hinge” refers to a thin,flexible hinge that joins two relatively more rigid parts together. Inone example, hinge 80 is a living hinge that is integrally formed withinner cannula body section 81 and inner cannula cutting section 83 byremoving a portion of the circumference of the inner cannula 76 along alength L (FIG. 11). Hinge 80 allows cutting section 83 to pivot abouthinge 80 as inner cannula 76 reciprocates within outer cannula 44. Asinner cannula 76 translates in the distal direction, it contacts tissuereceived in outer cannula opening 49 and encounters progressivelyincreasing resistance from the tissue as the tissue is urged in thedistal direction. As the resisting force of the tissue increases,cutting section 83 pivots progressively more until a zero annularclearance is obtained between inner cannula distal end 79 and outercannula opening 49. The received tissue is severed and aspirated in theproximal direction along inner cannula lumen 110 and received in tissuecollector 58. Thus, inner cannula lumen 110 provides an aspiration pathfrom the inner cannula distal end 79 to the inner cannula proximal end77. Hinge 80 allows a generally zero annular clearance to be obtainedbetween inner cannula distal end 79 and outer cannula opening 49 atcutting section 83 while not affecting the annular clearance betweeninner cannula body section 81 and outer cannula 44. This configurationmaximizes tissue cutting while minimizing frictional losses that wouldotherwise occur due to the fictional engagement of the outer surface ofinner cannula body section 81 and the inner surface of outer cannula 44if a very small annular clearance between the outer cannula 44 and innercannula 76 were present.

Outer cannula opening 49 may have a number of shapes. In certainexamples, when outer cannula opening 49 is viewed in plan, it has ashape that is generally square, rectangular, trapezoidal, ovular, or inthe shape of the letter “D.” In certain other exemplary implementations,outer cannula opening 49 is configured to direct tissue so that it maybe compressed as inner cannula 76 translates in the distal direction. Inone such implementation, depicted in FIGS. 10 and 12, outer cannulaopening 49 has a generally triangular shape when outer cannula opening49 is viewed in plan. As FIGS. 10 and 12 indicate, when viewed in plan,the width of opening 49 in a direction transverse to the outer cannulalongitudinal axis L₂ varies longitudinally along the length of outercannula 44, and preferably narrows from the proximal to distal portionsof opening 49. When viewed in side elevation, cutting edge 51 slopes ina radially outward direction moving distally along edge 51 in thedirection of longitudinal axis L₂. As a result, as a tissue sample isdistally urged within outer cannula opening 49 by the action of innercannula 76, the tissue is increasingly compressed in the direction ofthe circumference of inner cannula 76 (or in the direction of the“width” of opening 49 when viewed in plan). To ensure complete cutting,inner cannula distal end 79 preferably travels to a position that isdistal of outer cannula opening 49 during a tissue cutting operation,i.e., there is an inner cannula overstroke.

As mentioned above, tissue cutting device 40 aspirates tissue samplesreceived in inner cannula lumen 78 to cause the tissue samples to movein the proximal direction along the length of the inner cannula 76. Incertain methods of use, device 40 is used to resect tissue withoutcollecting tissue samples for further analysis. In such embodiments, atissue collector need not be provided. In other embodiments whereintissue collection is desired, device 40 preferably includes a tissuecollector 58 into which aspirated tissue samples are deposited during atissue cutting procedure. Tissue collector 58 may be located remotelyfrom handpiece 42 and outside the sterile field during a tissue cuttingoperation as shown in FIG. 21A. However, in an alternative embodiment,as best seen in the examples of FIGS. 1-7, tissue collector 58 isremovably connected to handpiece 42. In either embodiment, a fluidcollection canister 192 is preferably located between tissue collector58 and a source of vacuum (such as vacuum generator 153 in FIG. 21A) toprotect the vacuum generating apparatus from becoming contaminated ordamaged by aspirated fluids. In those embodiments that lack a tissuecollector, fluid collection canister 192 may be provided to collect bothaspirated fluid and tissue.

Referring to FIGS. 4-7, tissue collector 58 is connected to upperhousing 52 proximally of the inner cannula 76 to receive the aspiratedtissue samples. Tissue collector 58 is a generally cylindrical, hollowbody with an interior volume that is in fluid communication with theinner cannula lumen 78 and a source of vacuum (not shown in FIGS. 4-7).Tissue collector 58 is removably secured to housing connector 96 toallow for the periodic removal of collected tissue samples. Tissuecollector 58 is preferably secured to upper housing 52 in a manner thatprovides a substantially leak-proof vacuum seal to maintain consistentaspiration of severed tissue samples. A vacuum hose fitting 59 is formedon the proximal end of tissue collector 58 and is in fluid communicationwith the interior of tissue collector 58 and with a vacuum generator, aswill be discussed below.

In the embodiment of FIGS. 4-5, housing connector 96 is a generallycylindrical, flange extending proximally from upper housing 52. Uppershell 54 and lower shell 56 of upper housing 52 cooperatively define acavity into which a seal holder 94 is partially disposed. Seal holder 94includes a distal annular recess in which a seal 92, such as an o-ring,is disposed. Seal holder 94 also includes a central lumen through whichinner cannula 76 is slidably disposed. A proximally projecting portion95 of seal holder 94 projects away from upper housing 52 in the proximaldirection and is received within housing connector 96. As best seen inFIGS. 2 and 3, inner cannula proximal end 77 preferably remains withinseal holder 94 as inner cannula 76 reciprocates during operation oftissue cutting device 40. However, proximal end 77 moves within sealholder 94 as inner cannula 76 reciprocates. Seal 92 preferably comprisesa resilient material such as an elastomeric material. The sealingengagement of seal 92 and inner cannula 76 prevents air or fluids fromleaking between inner cannula 76 and upper housing 52 and aids inmaintaining consistent aspiration of samples through the inner cannulalumen 78.

Housing connector 96 includes connecting features 98 and 100 which areconfigured to engage with corresponding connecting features 102 and 104on tissue collector 58. In the embodiment of FIGS. 4 and 5, connectingfeatures 98 and 100 are “J” shaped slots formed in housing connector 96,and connecting features 102 and 104 are complementary protrusions formedon tissue collector 58 which engage connecting features 98 and 100,respectively. To connect tissue collector 58 to housing connector 96,protrusions 102 and 104 are aligned with slots 98 and 100, and tissuecollector 58 is then inserted into housing connector 96 in the distaldirection. Tissue collector 58 is then rotated to fully engageprotrusions 102 and 104 with slots 98 and 100. A seal 103 is providedaround the circumference of tissue collector 58 to sealingly engage theinner surface of housing connector 96.

An alternate embodiment of tissue collector 58 is depicted in FIGS. 6and 7. In the embodiment of FIGS. 6 and 7, tissue collector 58 issemi-elliptical in cross-section and includes a hollow interior forreceiving samples, as in the embodiment of FIGS. 4 and 5. In theembodiment of FIGS. 6 and 7, a cylindrical flange housing connector 96is not provided. Instead, upper housing 52 is formed with an engagementrecess 108 that engages a complementary clip 106 formed on tissuecollector 58. In each of the foregoing embodiments, tissue collector 58may be provided with a filter (not shown) in its interior for collectingsolid tissue samples while allowing liquids and gases (e.g., air) topass through. Exemplary filters include medical grade mesh filters witha mesh size smaller than that of tissue snippets 112.

In the embodiments of FIGS. 4-7, tissue collector 58 preferably has alongitudinal axis that is not collinear with the longitudinal axis L₁ ofhandpiece lower housing 50, motor 62, and cam 64. The longitudinal axisof tissue collector 58 is preferably substantially collinear with thelongitudinal axis L₂ of inner cannula 76 to yield an “in-line” filterconfiguration. Tissue collector 58 and inner cannula 76 are both spacedapart from and substantially parallel to the longitudinal axis L₁ ofhandpiece lower housing 50, motor 62, and cam 64. Thus, the cutting axis(i.e., the outer cannula longitudinal axis, which is collinear withupper housing longitudinal axis L₂) and sample aspiration path axisthrough inner cannula lumen 78 are not coaxial with the longitudinalaxis L₁ of the handpiece lower housing 50. As a result, when device 40is used to cut tissue, the surgeon's view of the cutting axis is notobstructed by his or her hand. As best seen in FIG. 28, the surgeon cantreat the proximal end of the upper housing 52 and/or filter 58 as a“gun sight” and align it with a tissue sample to be cut to thereby alignthe outer cannula 44 with the tissue sample, providing enhancedergonomic benefits over previous devices, in particular, previousneurosurgical devices. In the case of a device with a remote tissuecollector 58 such as the one depicted in FIGS. 21A and 21B, the user cantreat the proximal end of upper housing 52 as a gun sight and align itwith a target tissue.

When device 40 is used to cut tissue, outer cannula opening 49 must bealigned with the target tissue of interest to receive it for cutting.The entire device 40 can be rotated about the longitudinal axis ofhandpiece 42 to place outer cannula opening 49 at the desired location.However, this technique can be awkward and may reduce the surgeon'sdexterity. Thus, in an exemplary embodiment, device 40 includes aselectively rotatable outer cannula 44. As best seen in FIGS. 18-20, arotation dial 60 is provided and is rotatably seated in a cavity definedby upper shell 54 and lower shell 56 of upper housing 52. Rotation dial60 is configured such that when it is rotated, it causes outer cannula44 to rotate about its longitudinal axis L₂. Rotation dial 60 ispreferably connected to an outer cannula connector portion 88. In theembodiment of FIGS. 18-20, outer cannula connector portion 88 is asleeve that is integrally formed with rotation dial 60 and which isfixedly secured to outer cannula 44 such as by an adhesive or otherknown connection means. In the exemplary embodiment of FIG. 20 rotationdial 60 has an outer diameter that is greater than that of outer cannulaconnector portion 88.

As mentioned previously, inner cannula 76 includes a hinge 80 to allowinner cannula cutting section 83 to pivot toward outer cannula opening49 when device 40 is in operation. In order to ensure the correctoperation of hinge 80, the circumferential alignment of hinge 80 andouter cannula opening 49 should be maintained. Thus, rotation dial 60 ispreferably connected to inner cannula 76 such that when rotation dial 60is rotated, both outer cannula 47 and inner cannula 76 rotate in a fixedangular orientation with respect to one another by an amount thatdirectly corresponds to the amount by which rotation dial 60 is rotated.Rotation dial 60 may be directly connected to inner cannula 76 or mayuse an intervening connecting device. However, rotation dial 60 shouldbe configured to allow inner cannula 76 to reciprocate with respect torotation dial 60. As best seen in FIG. 20, rotation dial inner cannulaconnector 86 may be provided to connect rotation dial 60 to innercannula 76. Rotation dial inner cannula connector 86 comprises aproximal sleeve 87 disposed about inner cannula 76 and a distal,radially extending annular flange 90 with an outer diameter greater thanthat of the sleeve 87. Sleeve 87 and flange 90 may be in the shape ofcircular cylinders. Alternatively, and as shown in FIGS. 18-19, sleeve87 and flange 90 may be in the shape of a polygonal cylinder. Sleeve 87is slidably received within the annular cavity 130 at the distal end 126of the cannula transfer 74 and keyed to the inner surface of cannulatransfer 74 at annular cavity 130 such that sleeve 87 can reciprocatewith respect to cannula transfer 74 while causing cannula transfer 74 torotate with sleeve 87 when rotation dial 60 is rotated. When innercannula 76 is reciprocated, cannula transfer distal end 126 reciprocateswith respect to sleeve 87, thereby variably adjusting gap “G” definedwithin annular cavity 130 (FIG. 20). Alternatively, cannula transferdistal end 126 may be slidably received in an annular cavity formed insleeve 87 and may be keyed to the inner surface of the annular cavity sothat cannula transfer may reciprocate with respect to sleeve 87 whilestill rotating with sleeve 87 when dial 60 is rotates.

As best seen in FIG. 20, rotation dial 60 includes a first annularcavity 61 that is sized to receive and engage flange 90 in a closefitting relationship. Rotation dial 60 may be press fit to flange 90. Inaddition, adhesive connections or mechanical connections may be used.Because rotation dial 60 is directly or indirectly connected to bothouter cannula 44 and inner cannula 76, both cannulae rotate in directcorrespondence to the rotation of rotation dial 60, thereby allowing theuser to adjust the orientation of outer cannula opening 49 and innercannula hinge 80 in a circumferential direction with respect tohandpiece 42. As a result, surgeons need not rotate the entire tissuecutting device 40 to obtain the desired angular orientation.

Rotation dial 60, outer cannula 44, and inner cannula 76 are preferablyconfigured for 360° rotation. In addition, tactile indicators arepreferably provided on rotation dial 60 to allow a user to reliablydetermine the extent to which dial 60 has been rotated from a givenstarting point. The tactile indication may comprise surface featuresdefined on or in the exterior surface of rotation dial 60. In oneexemplary embodiment, depicted in FIGS. 18-20, a plurality of ridges 122is provided around the circumference of rotation dial 60 to providetactile indication. The ridges also act as grips and facilitate thesurgeon's ability to rotate the dial 60 without transferring unwantedmotion to the surgical site.

As mentioned previously, vacuum (sub-atmospheric pressure) is applied totissue collector 58 to aspirate severed tissue samples through innercannula 76 in the proximal direction. The application of vacuum to innercannula 76 via tissue collector vacuum hose fitting 59 will have apropensity to produce a vacuum at proximal end 45 of outer cannula 44 ifleakage occurs between inner cannula 76 and the components of upperhousing 52. The generation of a vacuum at outer cannula proximal end 45will in turn cause fluids and/or tissue samples at the distal end ofouter cannula 44 to flow into the annular clearance between innercannula 76 and outer cannula 44 that extends from its proximal end atouter cannula proximal end 45 to its distal end at inner cannula distalend 79. This fluid and/or tissue can result in blockage of the annularclearance and increased friction between the inner cannula 76 and outercannula 44, resulting in degraded performance. Accordingly, a seal 129is preferably provided to prevent air artifacts, fluid (water, saline,blood, etc.) flow, and tissue sample flow in the annular clearancebetween inner cannula 76 and outer cannula 44. The seal 129 ispreferably disposed adjacent the proximal end of the annular clearancebetween inner cannula 76 and outer cannula 44, i.e., proximally adjacentto outer cannula proximal end 45. As shown in FIG. 20, seal 129 ispreferably annular and circumscribes inner cannula 76, extending fromthe outer surface of inner cannula 76 in a radially outward direction aswell as longitudinally along a portion of the length of inner cannula76.

In the embodiment of FIG. 20, rotation dial 60 and sleeve 87 act as aseal housing and include a seal cavity 131 which is an annular cavitydisposed immediately adjacent to and distal of first annular cavity 61.Seal cavity 131 is sized to accept seal 129 therein. The seal 129 may bea conventional seal such as a solid, flexible and/or elastomeric o-ring.However, seal 129 is preferably amorphous and comprises a thixotropicmaterial that is a semi-solid. It is further preferred that seal 129fill the entirety of seal cavity 131 to ensure that cavity 131 issubstantially leak free. In the exemplary embodiment of FIG. 20, sealcavity 131 has an outer diameter that is greater than the outer diameterof outer cannula 44. Moreover, the annular thickness of seal cavity 131is preferably greater than the annular clearance between outer cannula44 and inner cannula 76 to better ensure complete sealing of the annularclearance.

In one exemplary embodiment, seal 129 is a grease—such as the so-called“high vacuum greases”—that is formulated to withstand vacuum conditions.Suitable high vacuum greases include halogenated polymers. Thehalogenated polymers are preferably based on cyclic ethers orunsaturated hydrocarbon polymeric precursors. In one exemplaryembodiment, a perfluroropolyether (PFPE) grease is used. Examples ofsuch greases include the FOMBLIN® family of greases supplied by SolvaySolexis, Inc. Other examples of such greases includepolytetrafluroroethylene greases (“PTFE”) such as TEFLON® greasessupplied by DuPont. One suitable high vacuum grease is FOMBLIN® Y VAC3grease, which is a PFPE grease with a PTFE thickener. The semi-solidseal 129 preferably has a kinematic viscosity at 20° C. of at leastabout 500 cSt, more preferably at least about 800 cSt, and even morepreferably at least about 1200 cSt. Semi-solid seal 129 preferably has akinematic viscosity at 20° C. of no greater than about 2500 cSt, morepreferably no greater than about 2000 cSt, and even more preferably nogreater than about 1700 cSt.

The use of a semi-solid seal 129 has several advantages. Because theseal is semi-solid, it will tend to absorb and dampen vibrationstransmitted from the reciprocation of the inner cannula, therebyreducing overall vibration of device 40, and in particular, thevibration transmitted to outer cannula 44. The dampening of suchvibrations is particularly beneficial because it prevents unwantedvibration of outer cannula 44 which can disturb delicate neurosurgicalprocedures. Moreover, because it is not a solid seal, seal 129 willexperience less heating and wear as it is frictionally engaged by thereciprocating inner cannula 76. In certain embodiments, a portion ofseal 129 will adhere to the outer surface of inner cannula 76 as itreciprocates producing a zero slip velocity condition at the innercannula 76 outer surface which may further reduce frictional heating anddegradation of seal 129. Because semi-solid seal 129 produces lessfrictional resistance to the reciprocation of inner cannula 76 ascompared to conventional solid seals such as o-rings, it also decreasesthe required motor power consumption and can facilitate the use of lowertorque and lower cost motors, which in turn facilitates making device 40disposable.

In one configuration, device 40 is connected to a vacuum source andconfigured for variable aspiration, i.e., configured to supply variablelevels of vacuum to inner cannula lumen 78. As depicted in FIG. 21A, inone exemplary implementation, a tissue cutting system is provided whichcomprises tissue cutting device 40, a tissue collector 58, a controller132, a vacuum generator 153, a vacuum actuator 144, a controllable valve146, a vacuum line 151, and a fluid collection canister 192. Asmentioned previously, in FIG. 21A tissue collector 58 is locatedremotely from handpiece 42 and may be placed far enough from thehandpiece 42 to remain outside of the sterile field during a tissuecutting operation. As best seen in FIG. 21B, tissue collector 58 isgenerally the same as the tissue collector 58 depicted in FIGS. 4-5.Vacuum line 151 a connects the distal end of tissue collector 58 toproximally projecting portion 95 of seal holder 94 on the proximal endof tissue cutting device upper housing 52. In one arrangement, theproximal end of vacuum line 151 a includes a hose fitting 59 b that isintegrally formed with a tissue collector coupler 296. Coupler 296 issimilar in structure to tissue collector connector 96 (FIGS. 4-5) and isa cylindrical structure with a hollow interior for receiving a portionof tissue collector 58. As best seen in FIG. 21B, tissue collector 58includes projections 202 and 204 which engage complementary slots 298and 200 in coupler 296 in the same manner that projections 102 and 104engage slots 98 and 100 in FIGS. 4-5. At the proximal end of tissuecollector 58, hose fitting 59 a engages vacuum line 151 b which in turnis connected to fluid collection canister 192. Fluid collection canister192 is connected to vacuum generator 153 via vacuum line 151 c. Vacuumgenerator 153 is connected to controllable valve 146 by way of pressureline 147.

The outlet of tissue collection canister 192 is preferably substantiallyliquid free and is connected to vacuum generator 153 via vacuum line 151c. Thus, vacuum generator 153 is in fluid communication with tissuecollector 58 and inner cannula lumen 78, thereby generating a vacuum atthe proximal end 77 of inner cannula 76 to aspirate severed tissuesamples from inner cannula distal end 79 to tissue collector 58. Thelevel of vacuum generated by vacuum generator is preferably variable andselectively controllable by a user. Maximum vacuum levels of at leastabout 0 in Hg. are preferred, and maximum vacuum levels of at leastabout 1 in Hg. are more preferred. Maximum vacuum levels of at leastabout 5 in Hg. are even more preferred, and maximum vacuum levels of atleast about 10 in Hg. are still more preferred. Maximum vacuum levels ofat least about 20 in. Hg. are yet more preferred, and vacuum levels ofat least about 29 in. Hg. are most preferred.

The controllable valve 146 and the vacuum generator 153 provide a meansfor continuously adjusting and controlling the level of vacuum appliedto tissue collector 58 and the proximal end of inner cannula lumen 78.Controllable valve 146 is supplied with a pressurized gas, preferablyair, or an inert gas such as nitrogen. In one exemplary embodiment, thepressure applied to controllable valve 146 is about 70 psi.

The system further includes an electrical controller 132 which receivesand provides signals to the various components to control or monitortheir operations. Controller 132 provides control signals to device 40via motor drive control line signal path 142 to activate or deactivatemotor 62. An aspiration valve control line 150 extends from thecontroller 132 to the controllable valve 146 which provides pressure tothe vacuum generator 153. Signals to the controllable valve 146 throughline 150 are used to control the amount of vacuum applied to tissuecollector 58.

Controller 132 also receives electrical signals from the variouscomponents of the system. For instance, a pressure transducer 148associated with the aspiration controllable valve 146, sends a signalalong line 152 to the controller 132. The signal is representative ofthe pressure supplied through controllable valve 146 to vacuum generator153. Thus, the transducer 148 provides immediate feedback to thecontroller which can in turn provide signals to aspiration controllablevalve 146.

The user can adjust the system operating parameters by using panelcontrols such as a console knob 138 and/or one or more depressiblecontrollers, such as a foot pedal 144. In one embodiment, foot pedal 144can be used to activate the motor 62 in device 40, causing the innercannula 76 to reciprocate within the outer cannula 44. In anotherembodiment, foot pedal 144 can be used to control the vacuum levelsupplied from vacuum generator 153 to tissue collector 58 and innercannula lumen 78. In another embodiment, foot pedal 144 can be used bothto activate motor 62 and to control the vacuum level supplied fromvacuum generator 153 to tissue collector 58. In one arrangement footpedal 144 is configured to variably increase the level of vacuum appliedto tissue collector 58 from a minimum level to a maximum level as footpedal 144 is depressed from a first position to a second position. Insuch an arrangement, the first position is one in which foot pedal 144is not depressed at all or is only slightly depressed, and the secondposition is one in which foot pedal 144 is fully depressed. In anotherembodiment, knob 138 is used to set a preselected maximum vacuum levelapplied by vacuum generator 153. Thus, by depressing foot pedal 144 froma first fully open position to a second fully closed position, aplurality (preferably a continuum) of vacuum levels can be supplied totissue collector 58 with the maximum vacuum level being user adjustablevia knob 138.

In one exemplary embodiment, foot pedal 144 includes two switches (notshown) for providing variable vacuum and activating motor 62. In oneexemplary embodiment, once foot pedal 144 is partially depressed from anopen or undepressed position, motor 62 is activated. In accordance withthe embodiment, continued depression of foot pedal 144 activates vacuumgenerator 153. Foot pedal 144 preferably provides continuous movementbetween a fully open and a fully depressed position which in turncorresponds to a plurality, and preferably a continuum, of vacuum levelsthat are supplied to inner cannula lumen 78. Once foot pedal 144 isfully depressed, the vacuum level supplied to inner cannula lumen 78corresponds to a previously selected maximum vacuum level.

In certain illustrative examples, the user will adjust the level ofvacuum to achieve a desired level of “traction” in the tissuesurrounding the tissue to be severed. As used here in, the term“traction” refers to the exertion of a pulling force on tissuesurrounding the target tissue to be severed. In some instances, tractionmay be visualizable by the surgeon with the use of a magnificationinstrument, such as a microscope or an endoscope. The level of vacuumwill also determine the amount of unsevered tissue that is drawn intoouter cannula opening 49, and therefore, the size of the severed tissuesnippets 112 (FIG. 14). Therefore, when fine shaving operations aredesired, the vacuum level will be a relatively lower level than ifdebulking (large scale tissue removal) is performed. Of course, thepre-selected maximum vacuum level will also affect the maximum size oftissue that is drawn into outer cannula opening 49, and therefore, willaffect the maximum size of severed tissue samples during any oneoperation. Also, the vacuum level may be adjusted based on theelasticity, fibrotic content, and hardness/softness of the tissue.

Console 134 may also include indicator lights 136, one of whichindicates the activation of cutting and one of which indicates theactivation of aspiration. Console 134 may further include an analogdisplay 140 with readouts for “aspiration” and “cutter.” The“aspiration” read out indicates the vacuum level supplied to tissuecollector 58 from vacuum generator 153. The “cutter” read out indicatesthe speed of reciprocation of inner cannula 76. In one embodiment, aspeed sensor is mounted in device 40 to determine the speed ofreciprocation of inner cannula 76 and the sensor is input to controller132.

As mentioned previously, when device 40 is used to perform a cuttingoperation, inner cannula 76 reciprocates within outer cannula opening 49to sever tissue received within outer cannula opening 49. When a cuttingoperation is complete, it may be preferred to have inner cannula 76 cometo rest at a position that is proximal of the non-cutting edge 53 ofouter cannula opening 49 to ensure that tissue is not trapped betweeninner cannula distal end 79 and outer cannula cutting edge 51. However,in certain methods of use, tissue cutting device 40 may be used as anaspiration wand without cutting any tissue. In these embodiments, thestop position of the inner cannula distal end 79 within outer cannulaopening 49 determines the open area of the outer cannula 44, andtherefore, the aspiration levels that can be applied immediatelyadjacent outer cannula opening 49. Thus, in some preferred embodiments,the inner cannula stop position is user adjustable. Tissue cuttingdevice 40 may be used to aspirate a variety of fluids associated with aneurosurgical procedure, including without limitation blood, saline,cerebrospinal fluid, and lactate ringer's solution. In certain examples,the inner cannula stop position is adjusted to provide a desired degreeof aspiration, outer cannula 44 is positioned proximate a target tissue,and vacuum is applied to manipulate the target tissue and draw it intoouter cannula opening 49. Outer cannula 44 is then moved to a desiredlocation or orientation, thereby moving the target tissue to the desiredlocation or orientation. Once the target tissue has been satisfactorilymanipulated, a cutting operation is initiated. By using device 40 inthis manner, target tissues can be drawn away from areas where tissuecutting operations are undesirable, and the cutting can be performedremotely from those areas.

In one exemplary system, an inner cannula position control is providedwhich controls the rest position of inner cannula 76 when motor 62 isdeactivated. Referring to FIG. 24, cam rotational position indicators176 a and 176 b are mounted on the proximal end of cam 64. In anexemplary embodiment, cam rotational position indicators 176 a and 176 bare magnets having opposite poles. A position sensor 174 is mounted onthe inner surface of cam housing 69 and generates a signal indicative ofthe rotational position of indicators 176 a and 176 b relative toposition sensor 174. As mentioned previously, the rotation of cam 64correlates directly to the position of inner cannula 76 within outercannula 44. Thus, the rotation of cam 64 can be sensed to indirectlydetermine the position of inner cannula 76. Accordingly, indicators 176a/176 b and sensor 174 can be used to determine the position of innercannula 76 with respect to non-cutting edge 53 of outer cannula opening49 (FIGS. 10-12).

Referring to FIG. 22, an embodiment of a system for controlling theoperation of tissue cutting device 40 is provided. The system includes amain control unit 158 (“MCU”), which (in the embodiment shown) isconfigured as a microprocessor-based system. In one implementation, MCU158 is incorporated in controller 132 and is operable to control thevarious operations of the tissue cutting device 40. Foot switch 144 iselectrically connected to a number of inputs of MCU 158 via an equalnumber, K, of signal paths 156, wherein K may be any integer. Panelcontrols, such as knob 138, are electrically connected to a number ofinputs of MCU 158 via an equal number, J, of signal paths 145, wherein Jmay be any integer.

Display unit 140 is electrically connected to a number of outputs of MCU158 via an equal number, Q, of signal paths 141, wherein Q may be anyinteger. In one exemplary implementation, depicted in FIG. 21A, displayunit 140 is provided on console 134.

As mentioned previously, tissue cutting device 40 includes motor 62coupled to the inner cannula 76 by an inner cannula drive assembly 63.The motor 62 is electrically connected to motor control unit 160 via anumber, M, of signal paths 142 wherein M may be any integer. The motorcontrol unit 160 is, in turn, connected to a number of outputs of MCU158 via an equal number, N, of signal paths 161. Cam rotational positionsensor 174 is electrically connected to a motor shaft position feedbackinput (SPF) of MCU 158 via signal path 162, and provides a motor stopidentification signal thereon as will be more fully describedhereinafter. The motor shaft stop identification signal provided bysensor 174 on signal path 162 preferably provides MCU 158 with a motorstop identification signal and may optionally provide a cutter speedsignal that is proportional to the motor speed for a geared system oridentical to the motor speed for a direct drive system.

Tissue cutting device 40 is further mechanically connected to a vacuumunit 168 (e.g., a combination of controllable valve 146 and vacuumgenerator 153 in FIG. 21A) via conduit 163, whereby the vacuum unit 168provides a controllable vacuum level to tissue cutting device 40 foraspirating tissue received in inner cannula lumen 78. Vacuum unit 168 iselectrically connected to a vacuum control unit 166 via a number, P, ofsignal paths 169 wherein P may be any integer. The vacuum control unit166 is, in turn, connected to a number of outputs of MCU 158 via anequal number, L, of signal paths 167, wherein L may be any integer. Avacuum sensor 164, which may be a temperature compensated solid-statepressure sensor, may be positioned within the vacuum line 151 andelectrically connected to a vacuum feedback (VF) input of MCU 158 viasignal path 165. Alternatively, the vacuum sensor 164 may be disposedwithin hand piece 42 or within the vacuum unit 168 itself.

In operation, the MCU 158 is responsive to a vacuum command signal,preferably provided by a corresponding control mechanism associated withcontrol panel 132, foot pedal 144, or an equivalent control mechanism,to provide one or more corresponding vacuum control signals to vacuumcontrol unit 166 along signal paths 167. The vacuum control unit 166, inturn, is responsive to the one or more vacuum control signals toactivate the vacuum unit 168 to thereby provide tissue cutting device 40with a desired level of vacuum. The actual vacuum level provided totissue cutting device 40 is sensed by vacuum sensor 164, which providesa corresponding vacuum feedback signal to the vacuum feedback input VFof MCU 158. The MCU 158 is then operable to compare the vacuum feedbacksignal with the vacuum command signal and correspondingly adjust the oneor more vacuum control signals to achieve the desired vacuum levelwithin tissue cutting device 40. Such closed-loop feedback techniquesare well known in the control systems art.

In one alternative embodiment, the MCU 158 can be replaced by individualmicroprocessors controlling the input and output for controlling theoperation of the motor 62 and the vacuum unit 168. In this alternativeembodiment, the motor control and vacuum control microprocessors can bePIC16CXX Series microcontrollers provided by Microchip, Inc. of ChandlerAriz. The motor control microcontrollers can receive input signals fromthe motor driver circuit 172 (FIG. 23) and position sensor 174, as wellas the foot switch 144 and panel controls 132. Likewise, the vacuummicrocontroller can receive input signals from the vacuum sensor 164,the foot switch 144 and panel controls 138. Each microcontroller canprovide its own output to its driven component and have its own display,such as an LED display, indicative of its operational status. Moreover,the two units can communicate with each other to ensure clean cutting byproper timing of the cutting and aspiration functions.

Referring now to FIG. 23, one exemplary embodiment of the motor controlunit 160 is shown in greater detail. The motor control unit 160 in oneembodiment includes a pulse width modulation (PWM) generator circuit 170having a motor speed input connected to one of the MCU outputs 161 ₁. Ifmotor speed control is provided, the output 161 ₁ can provide a variablevoltage signal indicative of a desired motor speed and based upon theposition of a throttle, foot pedal, or other actuator. In certainembodiments, an additional input is connected to another one of the MCUoutputs 161 ₂. The signal at this output 161 ₂ can be a motor slowdownsignal as described below. Alternatively, the output 161 ₂ canconstitute a braking signal used in connection with a current feedbackmotor controller. As a further alternative, the slowdown command may becommunicated via the motor speed command itself, rather than through aseparate signal 161 ₂. In this instance, the output 161 ₂ may not berequired.

In the illustrated embodiment, the PWM is disposed within the motorcontrol unit 160. Alternatively, the PWM can be integrated into the MCU158, or into the separate motor control microprocessor discussed above.In embodiments that include motor speed control, the motor speed inputreceives a motor speed signal from MCU 158 indicative of desiredoperational speed of the motor 62. The slowdown input can receive aspeed adjustment signal from the MCU 158 based on an actual motor speedsignal provided by a motor sensor associated with the motor 62.

A motor driver circuit 172 is electrically connected to PWM generatorcircuit 170 via signal path 173 and receives a PWM drive signaltherefrom, which is a pulse width modulated signal indicative of desiredmotor speed. The motor driver circuit 172 provides a motor drive signal(MD) to motor 62 via signal path 175. While the disclosed embodimentcontemplates digital control of the motor using the PWM generatorcircuit 170, alternative embodiments can utilize closed loop feedbackanalog circuits, particularly where slower cutting speeds arecontemplated.

The motor drive signal includes a motor stop input that is connected toanother one of the MCU outputs 161 ₁. In accordance with one aspect ofthe present disclosure, MCU 158 provides a motor stop signal on signalpath 161 ₃, based on a motor deactivation command provided by footswitch 144 or panel control 138 and also based on a motor stopidentification signal provided by sensor 174, to stop the inner cannula76 in a desired position, as will be more fully described hereinafter.In certain embodiments, only the motor stop signal is utilized tocommand the motor to stop at the predetermined position. In thesecertain embodiments, the motor slowdown signal on path 161 ₂ can beeliminated, or the input on path 161 ₂ can be used for other controlsignals to the motor control circuit.

As mentioned previously, when tissue cutting device 40 is deactivated,inner cannula 76 may come to rest partially disposed within outercannula opening 49. Referring to FIGS. 25-27, three different stoppositions of inner cannula 76 are shown. FIG. 27 shows that innercannula 76 can be stopped in a position in which a portion of the tissueT is trapped between the outer cannula opening 49 and the inner cannuladistal end 79. Efforts at withdrawing outer cannula 44 from the surgicalsite may accordingly result in tearing of the tissue portion T′ awayfrom the surrounding tissue base T. Surgeons encountering such trappingwould typically be required to re-activate tissue cutting device 40 torelease the tissue portion T′ from the surrounding tissue base T. Toprevent such tissue trapping from occurring, deactivation of the motor62 is controlled in such a manner that the inner cannula distal end 79is positioned remotely from the outer cannula opening 49 when innercannula 76 stops reciprocating. However, in certain methods of use,device 40 is used as an aspiration wand. In those methods, the stopposition of inner cannula distal end 79 may be adjusted to differentlocations within outer cannula opening 49 in order to adjust the levelof aspiration supplied to a region of the anatomy proximate outercannula opening 49. For example, stop positions may be selected thatlimit the percent open area of outer cannula opening 49 to 25%, 50%, or75% of the total area of opening 49.

Referring again to FIGS. 23 and 24, controlled deactivation of the motor62 will now be described in detail. When it is desired to deactivatetissue cutting device 40, a motor stop command is provided such as viafoot switch 144 or a panel control 138. In one embodiment, MCU 158 isresponsive to the motor stop command to provide a slowdown signal to thePWM generator via signal path 161 ₂ which slows the action of motor 62.Preferably, the slowdown signal corresponds to a predefined signal leveloperable to drive the motor 62 at a motor speed below a motor speedthreshold level. Since motor 62 is a brushed DC motor, it has arotational resistance or resistive torque associated therewith asdescribed above. In addition, in some cases friction between the innercannula 76 and outer cannula 44 will increase the rotational resistance.Due to this combined rotational resistance, operation of the motor 62will cease very rapidly or nearly instantly if the motor drive signal onsignal path 142 is disabled while driving motor 62 below the motor speedthreshold. Accordingly, when device 40 is used to cut tissue, alignmentof position indicators 176 a or 176 b with sensor 174 preferablycorresponds to a position of the tissue cutting device 40 at which thereis no danger of trapping tissue between inner cannula distal end 79 andthe outer cannula opening 49, and sensor 174 is operable to produce themotor stop identification signal when so aligned with indicator 176 a or176 b.

In one embodiment, MCU 158 is operable to produce a motor stop signal onsignal path 161 ₃ when sensor 174 detects alignment of positionindicators 176 a or 176 b therewith after one passage thereby ofindicator 176 a or 176 b since producing the slowdown signal on signalpath 161 ₂. Allowing one passage of indicator 176 a or 176 b by sensor174 after issuing the slowdown signal ensures that the rotational speedof motor 62 is at or below the motor speed threshold when subsequentlyissuing the motor stop command, regardless of the position of indicator176 a or 176 b relative to sensor 174 when the slowdown command wasissued. After one passage of indicator 176 a or 176 b by sensor 174since issuing the slowdown signal, MCU 158 is responsive to the signalprovided by sensor 174 indicative of alignment of indicator 176 a or 176b therewith, to produce the motor stop signal on signal path 161 ₃. Themotor driver 172 is responsive to the motor stop signal to produce amotor disable signal on signal path 175. Due to the inherent rotationalresistance, motor 62 is responsive to the motor disable signal toimmediately cease operation thereof with indicator 176 a or 176 bsubstantially aligned with sensor 174, and with the inner cannula 76accordingly positioned so as not to trap tissue between inner cannuladistal end 79 and the outer cannula opening 49.

As mentioned above, in one exemplary embodiment, the inner cannula stopposition is user adjustable, such as by adjusting a panel control 138 onconsole 134. In accordance with the embodiment, it is contemplated thatthe stopped rotational position of cam 64, and therefore the innercannula distal end 79, may be instead aligned with a predetermineddifferential distance between the indicator 176 a/176 b and the sensor174. The braking characteristics of the inner cannula 76 and motor 62can be ascertained and the stopping distance determined so that thispredetermined differential distance can be calibrated accordingly.However, in a preferred embodiment, when inner cannula 76 comes to rest,the distal end 79 is located proximally of the outer cannula opening 44by a predetermined distance, as shown in FIG. 26.

A method of using device 40 to perform a tissue cutting procedure willnow be described in the context of a neurosurgical procedure involvingthe cutting of a neurological target tissue. In one example, the targettissue is brain tissue, and in another example the target tissue isspinal tissue, for example, the tissue of an intervertebral disk. Incertain exemplary methods, the tissue specimen being cut is a tumor or alesion.

In accordance with the method, it is first determined whether thecutting operation will be a debulking operation or a fine shavingoperation or a cutting operation that is somewhere in between adebulking and fine shaving operation. A full surgical procedure maycombine a variety of these procedures. A surgical access path is thencreated to the tissue sample of interest. In one embodiment, thesurgical path is created and/or the target tissue is accessed using an“open” procedure in which the target tissue is open to the atmosphere(e.g., a full open craniotomy). In another embodiment, the surgical pathis created and/or the target tissue is accessed using a “closed”procedure in which the target tissue is sealed from the atmosphere.

At this point, the distal end 79 of inner cannula 76 is locatedproximally of outer cannula opening 49 due to the use of an innercannula stop position control of the type described previously. Themaximum vacuum level to be applied to device 40 is then set using panelcontrols 138. Generally, higher vacuum levels will be used for debulkingprocedures than for fine shaving procedures as higher vacuum levels willtend to draw relatively larger sections of tissue into outer cannulaopening 49. In one embodiment, the panel control 138 is a knob onconsole 134 that is rotated to set the desired maximum vacuum level.

In one arrangement, device 40 is configured to be gripped with a singlehand during a tissue cutting procedure. A variety of different grips maybe used, examples of which are provided in FIGS. 29A-29C. Referring toFIG. 29A, in one example, device 40 is gripped by wrapping the fourfingers of one hand around the proximal end 46 of lower housing 50 withdevice 40 resting in the palm of the user's hand. In this configuration,the pinky finger is spaced apart from the proximal end of lower housing50 and is located adjacent the midpoint MP of the lower housing 50. Thethumb is spaced apart from midpoint MP and is adjacent the proximal endof lower housing 50. In FIG. 29A, the thumb is located adjacently distalto hose connector 43. In the configuration of FIG. 29A, the right handis used to grip device 40, and when viewed from the proximal end oflower housing 50, the fingers of the hand wrap around the lower housing50 in a counterclockwise direction. If the left hand were used, thefingers would wrap around lower housing 50 in the opposite (e.g.,clockwise) direction.

Referring to FIG. 29B, another single-hand gripping orientation isdepicted. The depicted orientation is similar to the grip that is usedto hold a writing instrument, such as a pen or pencil. The index fingerengages a portion of the upper housing 52 and the thumb engages aportion of the upper housing 52 and/or a portion of lower housing 50.The index finger and thumb are preferably spaced apart in a directionthat is perpendicular to upper housing longitudinal axis L₂. Proximalportion 46 of lower housing 50 rests between the base of the indexfinger and the base of the thumb. In one preferred example, the grip ofFIG. 29B is used when the center of gravity of device 40 is distal oflower housing midpoint MP. The grip of FIG. 29B allows the device 40 tobe used for delicate shaving and debulking procedures in whichrelatively precise manipulation of device 40 is desirable. In addition,when held in the grip of FIG. 29B, rotation dial 60 can be readilyrotated with the index finger to adjust the circumferential orientationof the cannulae 44 and 76 without using a second hand or repositioningthe fingers of the gripping hand.

Referring to FIG. 29C, a further single-hand gripping orientation isdepicted. In this orientation, the thumb is positioned generally asdescribed and depicted with respect to FIG. 29B. However, the tip of theindex finger engages the lower housing 50 instead of upper housing 52.The index finger and thumb are again spaced apart from one another in adirection that is perpendicular to the longitudinal axis L₂ of upperhousing 52, and the proximal housing section 46 rests between the baseof the thumb and index finger. For additional support, the medial sideof the middle finger is also placed against the lower housing 50.

After grasping handpiece 42, the surgeon may use the proximal end ofupper housing 52 to align the outer cannula 44 with the target tissue.Referring to FIG. 28, the surgeon may view the proximal end of upperhousing 52 and use it as a “gun sight” to perform the alignment. Thesurgeon will then insert outer cannula 44 to a location proximate thetarget tissue. Depending on the hand and the surgeon's orientation withrespect to the target tissue, the surgeon may then rotate dial 60 torotate outer cannula 44 about its own longitudinal axis L₂ and orientouter cannula opening 49 immediately adjacent the target tissue. Therotation of outer cannula 44 with dial 60 causes inner cannula 76 torotate such that a fixed rotational or angular relationship ismaintained between inner cannula 76 and outer cannula 44. Once theopening 49 is in the desired orientation, the motor 62 is activated, forexample, by beginning to depress pedal 144 from its fully undepressed(open) position to a second partially depressed position which causesmotor control unit 160 to send a signal to motor 62 on signal path 142.Motor 62 may also be activated by a panel control 138. The rotation ofmotor 62 causes cam 64 to rotate, resulting in the reciprocation of camfollower 68 and cam transfer 72. The reciprocation of cam transfer 72causes cannula transfer 74 to reciprocate, thereby reciprocating innercannula 76 within outer cannula lumen 110.

Once motor 62 is activated, vacuum is supplied to inner cannula lumen78. In one embodiment, as the pedal 144 is further depressed (beyond theposition at which motor 62 is activated), vacuum generator 153 isactivated. The surgeon then adjusts the degree of depression of the footpedal 144 to obtain the desired level of vacuum by visualizing themovement of the target tissue relative to the outer cannula opening 49.In certain embodiments, the surgeon controls the vacuum level to obtaina desired amount of traction in the tissue surrounding the targettissue. If the surgeon desires to apply the previously set maximumvacuum level, he or she depresses pedal 144 to its fully depressedposition.

If desired, the surgeon may depress and partially release the pedal 144a number of times to manipulate the target tissue in a satisfactorymanner. Open loop or closed loop vacuum control may be provided. In oneexample, closed loop control is used. In accordance with the example,vacuum control unit 166 is manipulable to adjust the setpoint of vacuumgenerator 153 which is manipulable to adjust the inner cannula vacuumlevel along a continuum of levels below the pre-selected maximum level.In one embodiment, the extent of depression of foot pedal 144 dictatesthe vacuum set point supplied to vacuum control unit 166 on signal path167, and therefore, the amount of vacuum provided by vacuum unit 168.Vacuum sensor 164 measures the vacuum supplied to tissue collector 58and feeds a signal back to main control unit 158 on signal path 165. Themeasured vacuum is then compared to the set point applied to vacuumcontrol unit 166 via foot pedal 144, and the signal transmitted tovacuum generator 153 is then adjusted to move the measured vacuum valuetowards the set point. To obtain a vacuum level equal to the maximumpre-set level, pedal 144 is completely depressed.

In another example, the vacuum system is operated in an open loopmanner. In accordance with the example, pedal 144 directly adjustsvacuum unit 166. In one implementation, pedal 144 variably adjusts theamount of pressure supplied to controllable valve 146. The variation inpressure in turn affects the vacuum provided by vacuum generator 153 toinner cannula lumen 78. As with the closed loop example, the system maybe configured to allow the user to set a maximum vacuum that is obtainedwhen pedal 144 is fully depressed.

Maximum vacuum levels of at least about 0 in Hg. are preferred, andmaximum vacuum levels of at least about 1 in Hg. are more preferred.Maximum vacuum levels of at least about 5 in Hg. are even morepreferred, and maximum vacuum levels of at least about 10 in Hg. arestill more preferred. Maximum vacuum levels of at least about 20 in. Hg.are yet more preferred, and vacuum levels of at least about 29 in. Hg.are most preferred.

Due to the resistance of the tissue drawn into outer cannula opening 49,cutting section 83 pivots about hinge 80 and toward outer cannulaopening 49 as inner cannula 76 travels in the distal direction. Theinner cannula cutting section 83 continues to pivot as it travels in thedistal direction, eventually compressing tissue within outer cannulaopening 49 and severing it. The severed tissue forms a continuum oftissue snippets 112 (FIG. 14) within inner cannula lumen 78. Due to thevacuum applied to tissue collector 58, snippets 112 are aspiratedthrough inner cannula lumen 78 in the proximal direction. Theyeventually exit inner cannula lumen 78 at inner cannula proximal end 77and enter tissue collector 58 (or fluid collection canister 192 if nocollector 58 is provided). Any fluids that are aspirated exit tissuecollector 58 and are trapped in fluid collection canister 192. Thesurgeon preferably severs tissue at a cutting rate of at least about1,000 cuts/minute. Cutting rates of at least about 1,200 cuts/minute aremore preferred, and cutting rates of at least about 1,500 cuts/minuteare even more preferred. Cutting rates of less than about 2,500cuts/minute are preferred. Cutting rates of less than about 2,000cuts/minute are more preferred, and cutting rates of less than about1,800 cuts/minute are even more preferred.

The surgeon may move device 40 around the target tissue until thedesired degree of cutting has been completed. Motor 62 is thendeactivated, for example, by completely releasing pedal 144 so itreturns to its fully undepressed (open) position. If an inner cannulastop position control is provided, inner cannula 76 preferably comes torest proximally of outer cannula opening 49, as shown in FIG. 26. Outercannula 44 is then removed from the surgical site. Tissue collector 58is then removed from upper housing 52 of handpiece 42, and the collectedtissue samples are either discarded or saved for subsequent analysis.Fluids collected in canister 192 are preferably discarded. If the remotetissue collector of FIG. 21A is used, tissue samples may be removed fromit without removing outer cannula 44 from the surgical site or otherwisedisturbing the surrounding tissue.

In certain exemplary methods, tissue cutting device 40 may be used withan imaging device, for example, a video camera or a magnificationinstrument such as a microscope or an endoscope. The imaging device aidsthe surgeon in visualizing the target tissue to be resected and allowsfor more precise surgical techniques. Tissue cutting device 40 isadvantageously grippable and manipulable with one hand, allowing thesurgeon to manipulate an imaging device with his or her other hand. Asmentioned previously, the offsetting of the cannulae 44 and 76 from thelower housing 50 allows the device to be shortened relative to otherdevices. Thus, device 40 is more readily manipulable in restrictedspaces that are sometimes encountered in imaging device-assistedneurosurgical procedures.

Referring to FIG. 30, an endoscope 300 for use with tissue cuttingdevice 40 is depicted. Endoscope 300 comprises a housing 301, aneye-piece 302, a fiber optic cable connector 304, and a shaft 306. Shaft306 includes a proximal end 308 which is disposed in and connected tohousing 301. Shaft 306 further includes a distal end 310 spaced apartfrom proximal end 308. Endoscope 300 is configured to allow a user toview a surgical area of interest proximate distal shaft end 310 througheye-piece 302. Shaft 306 includes a conduit (not separately shown) fortransmitting light provided via fiber optic connector 304 to thesurgical area. Shaft 306 also includes a lens (not separately shown) formagnifying and viewing the surgical area. Eye-piece 302 is pivotallyconnected to housing 301 at pivot axis 305, allowing eyepiece 302 to beadjusted to various positions about pivot axis 305. As a result,eye-piece 302 can be moved toward distal shaft end 310 or away fromdistal shaft end 310. Eye-piece 302 may also be connected to a camerawith a camera connector so that the image generated by endoscope 300 canbe viewed on a display monitor.

To facilitate the use of endoscope 300 in surgical procedure, trocar 307may be provided, as best seen in FIGS. 31A and 31B. Trocar 307 isespecially useful for closed surgical procedures. Trocar 307 comprises atrocar body 314 and a trocar shaft 312. Trocar 307 has a proximal end316 with a proximal opening formed in trocar body 314 and a distal end318 on shaft 312. Shaft 312 defines one or more channels in itsinterior. Trocar body 314 is sized to accommodate irrigation conduit 320as well as endoscope 300 and tissue cutting device 40. As shown in FIG.31B, shaft 312 has a plurality of channels, 324, 326, 328, and 330 whichterminate at tip distal face 322. Working channel 324 is sized toaccommodate outer cannula 44 of tissue cutting device 40. Channel 326 issized to accommodate endoscope shaft 306. Channel 328 is an irrigationchannel used to direct irrigation fluid from irrigation conduit 320 tothe surgical site. Channel 330 is a relief channel used to relieve fluidpressure at the surgical site. During closed procedures, as irrigationfluid flows to a surgical site it can pressurize the site. If leftunchecked, such pressurization can result in tissue and/or neurologicaldamage. Thus, relief channel 330 provides a fluid path to relievepressure build up at the surgical site.

In certain examples, tissue cutting device 40 is combined with animaging device to define a tissue cutting and imaging assembly 303 thatis capable of simultaneously imaging and cutting a target tissueassociated with a patient's neurological system. Because assembly 303effectively combines both imaging and cutting operations into a single,integral device, it is particularly advantageous in performing closedprocedures where a surgical access path is created percutaneously.

Referring to FIG. 32, a tissue cutting and imaging assembly 303 isdepicted. Cutting and imaging assembly 303 comprises tissue cuttingdevice 40, trocar 307, and endoscope 300. As shown in the figure,endoscope 300 is inserted through trocar 307 via endoscope channel 326such that endoscope distal end 310 exits through and projects away fromtrocar 307 at trocar shaft distal tip face 322. Tissue cutting device 40is connected to trocar 307 such that outer cannula 44 is inserted in theopen proximal end 316, through trocar body 314, and through workingchannel 324 of trocar shaft 312. Distal end 47 of the outer cannula 44of tissue cutting device 40 projects through and away from shaft distalend 318 of trocar 307 at trocar shaft distal tip face 322.

Although various configurations are possible, in the cutting and imagingsystem 303 of FIG. 32, tissue cutting device 40 is positioned with aproximal portion of outer cannula 44 adjacent to endoscope housing 301.Proximal end 319 of endoscope housing 301 is positioned distally of andadjacent to front housing 55 of tissue cutting device handpiece 42.

A method of using the cutting and imaging assembly 303 of FIG. 32 toperform a tissue cutting procedure will now be described in the contextof a neurosurgical procedure involving the cutting of a neurologicaltarget tissue. In one example, the target tissue is a brain tissue. Inanother example, the target tissue is spinal tissue, for example, thetissue of an intervertebral disk. In certain exemplary methods, thetissue specimen being cut is a tumor or lesion.

As with the previous method of use discussed above, it is firstdetermined whether the cutting operation will be a debulking operation,a fine shaving operation, or an operation that is somewhere in between adebulking operation and a fine shaving operation. In addition, any givensurgical procedure may combine various debulking and fine shavingoperations. Based on the nature of the cutting operation, the user mayset a maximum vacuum level in the manner described previously.

Tissue cutting and imaging assembly 303 is provided in the form in whichit appears in FIG. 32. A surgical access path is created and/or thetarget tissue is accessed using an open procedure or a closed procedure,as explained previously. However, tissue cutting and imaging assembly303 is especially suited for closed procedures. In one example, thesurgeon places one eye at eye-piece 302 and manipulates trocar shaft 312to position distal trocar tip 318 proximate the target tissue. At thispoint, distal end 79 of inner cannula 76 is located proximally of outercannula opening 49 due to the use of inner cannula stop position controlof the type described previously. The maximum vacuum level to be appliedto device 40 is then set using panel controls 138. As mentionedpreviously, higher vacuum levels will generally be used for debulkingprocedures while relatively lower vacuum levels will be used for fineshaving procedures. In one method, device 40 is configured to be grippedwith a single hand so as to allow simultaneous manipulation of endoscope300, trocar 307, and tissue cutting device 40. A variety of differentgrips may be used, as discussed previously with respect to FIGS.29A-29C.

Depending on the selected hand and the surgeon's position with respectto that of the target tissue, dial 60 may be rotated to rotate outercannula 44 about its own longitudinal axis and to orient outer cannulaopening 49 immediately adjacent the target tissue. As discussedpreviously, the tissue removal device 40 is preferably configured suchthat when outer cannula 44 rotates, inner cannula 76 also rotates tomaintain a fixed angular orientation between outer cannula 44 and innercannula 76. Once the opening is in the desired position, motor 62 isactivated in the manner described previously. Vacuum generator 153 isthen activated and foot pedal 144 is used to obtain the desired level ofvacuum. In one example, the surgeon views the target tissue througheyepiece 302 to visualize the tissue's response (e.g., traction) tovarious levels of vacuum and select a desired level. The vacuum levelsare the same as those described previously.

Due to the application of vacuum, the target tissue proximate trocardistal end 318 is drawn into outer cannula opening 49. As inner cannula76 travels in the distal direction, it compresses tissue received withinouter cannula opening 49, causing inner cannula 76 to pivot about hinge80 and sever the received tissue in to discrete tissue samples such astissue snippets. As described earlier with reference to FIG. 14, tissuesnippets 112 are aspirated through inner cannula lumen 78 in theproximal direction due to the application of vacuum. Snippets 112eventually enter tissue collector 58 (or fluid collection canister 192if a remote collection system such as that of FIG. 21A is used). Thetissue cutting rates are preferably those described previously. Ifdesired an irrigation fluid such as saline may be fed to the targettissue area via irrigation conduit 320.

Endoscope 300 is configured to allow a surgeon to view the target tissuethrough eye-piece 302. However, a camera may also be connected to acamera connector (not shown) attached to eyepiece 302 allowing the imagegenerated by endoscope 300 to be viewed on a display monitor. Inaccordance with one example, the surgeon views the target tissue on thedisplay monitor while manipulating cutting and imaging system 303 andcutting tissue.

In certain examples, device 40 is configured such that its outer cannula44 can be accommodated by working channels in known trocars. In certainembodiments, working channel 324 has an inner diameter of less than 8mm, preferably less than 6 mm, more preferably less than 4 mm, and mostpreferably about 2 mm, and outer cannula 44 has an outer diameter thatallows outer cannula 44 to be slidably received in working channel 324.In other examples, outer cannula 44 is at least as long as known workingchannels. In certain embodiments, outer cannula 44 is at least about 6inches, preferably at least about 8 inches, more preferably at leastabout 10 inches, and even more preferably at least about 12 inches inlength. Unlike many known neurosurgical devices such as rotrary shaversor ultrasonic devices, in certain exemplary implementations, owing tothe rate of reciprocation and the inclusion of hinge 80, tissue cuttingdevice 40 is capable of cutting tissue samples having at least onedimension that is smaller than the inner diameter of inner cannula 76while having an outer cannula 44 diameter that is small enough to fitinto the working channels of known trocars.

Tissue cutting and imaging assembly 303 is useful in a number ofprocedures, but is especially beneficial in closed procedures. In oneexemplary method, tissue cutting and imaging assembly 303 is used toperform closed, percutaneous tissue cutting procedures in the thirdventricle of the brain. Such procedures include removing tumors andmembranes in the third ventricle. In addition, cerebrospinal fluidcirculates through the third ventricle and into the spinal column. Incertain patients, occlusions can form in the third ventricle, blockingthe fluid circulation. Tissue cutting and imaging assembly 303 may beused to remove such occlusions and restore circulation. Other closedprocedures for which tissue cutting and imaging assembly is particularlywell suited include the removal of tumors from the hypothalamus.

As mentioned previously, tissue cutting device 40 may be operated as avariable aspiration wand. This mode of operation may be particularlyuseful if tissue cutting and imaging device 303 is provided. In onemethod, tissue cutting device 40 is operated in both a tissue cuttingmode and in an aspiration wand mode (i.e., the inner cannula 76 is notreciprocating) without being removed from working channel 324 betweenmodes. In addition, the inner cannula stop position may be adjusted toobtain a desired degree of aspiration or vary the degree of aspiration,and therefore, the vacuum level applied to inner cannula lumen 78. Thisavoids a difficulty present in certain existing methods wherein acutting device must be removed from the working channel so that aseparate aspiration wand may be inserted in it.

In accordance with another method, endoscope 300 and tissue cuttingdevice 40 may be independently manipulated by a surgeon without beingcombined into an integral cutting and imaging assembly 303. Referring toFIG. 34A, surgeon 340 grips tissue cutting device handpiece 42 in onehand while holding endoscope 300 (or holding trocar 307 with an insertedendoscope 300) in the other hand. A variety of grips may be used to holddevice 40 as described above. An articulating arm 360 may be connectedto a heavy or relatively stationary object such as cabinet 364.Articulating arm 360 is connected to trocar 307 via connector 321 whichmay be any known type of connector. As shown in FIG. 34B, distal end 310of endoscope shaft 306 is positioned proximate target tissue 342 toallow it to be visualized by endoscope 300 (and, optionally, on monitor345 if a camera connection is provided). The distal end 47 of tissuecutting device outer cannula 44 is positioned in a line of sight definedbetween distal endoscope end 310 and target tissue 342 to allow thetarget tissue to be visualized as it is manipulated and/or cut by tissuecutting device 40. In one exemplary method, endoscope 300 is positionedsuch that the entire length of outer cannula 44 is disposed betweenendoscope eyepiece 302 and target tissue 342 in a direction along thelongitudinal axis of endoscope 300. Once tissue cutting device 40 ispositioned as desired, the reciprocation of the inner cannula 76 can beinitiated, and vacuum can be applied to cut target tissue 342 in themanner described previously. If desired, endoscope 300 can be used toview target tissue 342 before and/or during reciprocation of innercannula 76. Tissue cutting device 40 may be operated in a tissue cuttingmode and in an aspiration wand mode without removing outer cannula 44from the field of view defined between distal endoscope tip 310 andtarget tissue 342.

As mentioned previously, an irrigation fluid may be supplied to thesurgical site via irrigation channel 328 in trocar 307. If the pressureat the surgical site becomes too great, relief channel 330 will relieveat least some of the excess fluid to drop the pressure. In addition,device 40 may provide additional pressure relief. As mentionedpreviously, in certain exemplary embodiments wherein device 40 isoperated at reciprocation rates of 1500 reciprocations/minute or more,the combination of the reciprocation rate and the inclusion of a hingedinner cannula produces discrete tissue samples having at least onedimension that is less than the inner diameter of inner cannula 76. Insuch cases, there will be a fluid flow path around the severed tissuesamples as they are aspirated through inner cannula 76. This fluid flowpath provides an additional mechanism for relieving excess pressure atthe surgical site, which can be helpful if relief channel 330 is atcapacity or becomes occluded.

As discussed earlier, tissue cutting device 40 may also be used withmicroscopes during tissue cutting and removal procedures. One suchprocedure is an open craniotomy, an example of which is depicted inFIGS. 33A-33B. A surgical opening to target tissue 342 is created in thepatient's cranium to provide access to the target tissue to be removed.In order to better visualize the target tissue, microscope 344 isprovided. A variety of different microscope designs and configurationsmay be used, and the microscope depicted in FIG. 33A is merelyexemplary. Microscope 344 includes eyepieces 346 a and 346 b throughwhich surgeon 340 visualizes the target tissue. Lens 348 is provided tomagnify the target tissue image provided to eyepieces 346 a and 346 b.Microscope 344 is positioned such that a line of sight 350 is definedbetween lens 348 and target tissue 342. While viewing the target tissuethrough one of the eyepieces 346 a, 346 b, surgeon 340 grips tissuecutting device 40 in one hand and positions the distal end 47 of outercannula 44 such that outer cannula opening 49 is proximate the targettissue 342. The variety of grips described earlier may be used to holddevice 40. If necessary, rotation dial 60 is used to adjust thecircumferential position of outer cannula opening 49 with respect totarget tissue 342. In certain exemplary embodiments, outer cannula 44has a length that is less than the distance between lens 348 and targettissue 342, allowing surgeon 340 to better manipulate tissue cuttingdevice 40 without inadvertently contacting lens 348. In otherembodiments, tissue cutting device 40 has a length that is less than thedistance between lens 348 and target tissue 342.

Once device 40 is positioned as desired relative to target tissue 342,device 40 is activated in the manner described previously to cause thegeneration of vacuum in inner cannula lumen 78 and the reciprocation ofinner cannula 76 within outer cannula 44. Target tissue 342 is thenreceived in outer cannula opening 49 and severed by the cutting edge ofinner cannula distal end 79. Severed tissue samples are then aspiratedand collected by tissue collector 58 (which may be attached to device 40or positioned remotely from it). In certain examples, target tissue 342is viewed with microscope 344 before inner cannula 76 beginsreciprocating within outer cannula 44. In other examples, target tissue342 is first viewed prior to reciprocation and then viewed again duringreciprocation. As discussed previously, in certain implementations,tissue cutting device 40 is capable of cutting small snippets of tissue.Unlike certain known devices, in certain examples device 40 isparticularly well suited for use with imaging devices such asmicroscopes and endoscopes because the size of the severed tissuesamples is more commensurate with the level of magnification provided.Thus, tissue cutting may occur on a smaller scale and can be viewed athigher magnifications. Device 40 may provide a synergistic effect whenused with imaging devices because it is manipulable in smaller spacestypically encountered in some imaging device-assisted neurologicalprocedures and because it allows for more refined and smaller scaletissue cutting. In those exemplary implementations wherein device 40 isoperable as a variable aspiration wand, it may be operated both in atissue cutting mode and in an aspiration mode without being removed fromthe field of view of the imaging device.

It will be appreciated that the tissue cutting devices and methodsdescribed herein have broad applications. The foregoing embodiments werechosen and described in order to illustrate principles of the methodsand apparatuses as well as some practical applications. The precedingdescription enables others skilled in the art to utilize methods andapparatuses in various embodiments and with various modifications as aresuited to the particular use contemplated. In accordance with theprovisions of the patent statutes, the principles and modes of operationof this invention have been explained and illustrated in exemplaryembodiments.

It is intended that the scope of the present methods and apparatuses bedefined by the following claims. However, it must be understood thatthis invention may be practiced otherwise than is specifically explainedand illustrated without departing from its spirit or scope. It should beunderstood by those skilled in the art that various alternatives to theembodiments described herein may be employed in practicing the claimswithout departing from the spirit and scope as defined in the followingclaims. The scope of the invention should be determined, not withreference to the above description, but should instead be determinedwith reference to the appended claims, along with the full scope ofequivalents to which such claims are entitled. It is anticipated andintended that future developments will occur in the arts discussedherein, and that the disclosed systems and methods will be incorporatedinto such future examples. Furthermore, all terms used in the claims areintended to be given their broadest reasonable constructions and theirordinary meanings as understood by those skilled in the art unless anexplicit indication to the contrary is made herein. In particular, useof the singular articles such as “a,” “the,” “said,” etc. should be readto recite one or more of the indicated elements unless a claim recitesan explicit limitation to the contrary. It is intended that thefollowing claims define the scope of the invention and that the methodand apparatus within the scope of these claims and their equivalents becovered thereby. In sum, it should be understood that the invention iscapable of modification and variation and is limited only by thefollowing claims.

What is claimed as new and desired to be protected by Letters Patent ofthe United States is:
 1. A tissue removal device, comprising: ahandpiece having a housing, the housing having a longitudinal axis, aproximal end including a proximal-most portion, a distal end, and amidpoint along the longitudinal axis, wherein the proximal-most portionof the housing includes one of a cable port and a hose connector; anouter cannula having an outer cannula lumen, a proximal end, a distalend, and an outer cannula opening adjacent the distal end, wherein theopening adjacent the distal end defines a cutting edge for severingtissue; an inner cannula disposed in the outer cannula lumen andreciprocable within the outer cannula lumen, the inner cannula having alongitudinal axis, an inner cannula lumen, a proximal end, an opendistal end, a cutting edge at the distal end, a living hinge, a cuttingsection, and a body section, with the hinge being located between thecutting section and the body section, wherein the cutting section ispivotable when the inner cannula reciprocates within the outer cannulalumen; a tissue collector in fluid communication with the inner cannulalumen; and a motor disposed in the handpiece; wherein the motor ispositioned proximal of the housing midpoint along the direction of thehousing longitudinal axis.
 2. The tissue removal device of claim 1,wherein the housing is a lower housing, the handpiece further comprisesan upper housing connected to the lower housing, and the outer cannulais partially disposed in the upper housing and projects away from theupper housing along the direction of the inner cannula longitudinalaxis.
 3. The tissue removal device of claim 1, wherein the housinglongitudinal axis is spaced apart from the inner cannula longitudinalaxis in a direction that is substantially perpendicular to the innercannula longitudinal axis.
 4. The tissue removal device of claim 1,wherein the housing longitudinal axis is spaced apart from andsubstantially parallel to the inner cannula longitudinal axis.
 5. Thetissue removal device of claim 1, wherein the tissue collector has alongitudinal axis, and the tissue collector longitudinal axis issubstantially collinear with the inner cannula longitudinal axis.
 6. Thetissue removal device of claim 1, further comprising a drive assemblydisposed in the housing, wherein the drive assembly is located betweenthe midpoint of the housing and the distal end of the housing.
 7. Thetissue removal device of claim 6, wherein the drive assembly comprises acam, and the rotation of the motor causes the cam to rotate.
 8. Thetissue removal device of claim 7, wherein the cam has a length, asurface, a continuous channel defined in the surface, two cam channelapexes that are spaced apart from one another along the length of thecam, and a longitudinal axis, and the cam longitudinal axis issubstantially parallel to and spaced apart from the inner cannulalongitudinal axis.
 9. The tissue removal device of claim 8, furthercomprising a cam follower connected to the inner cannula, wherein thecam follower is disposed in the cam channel and moves along the channelwhen the cam rotates about the cam longitudinal axis.
 10. The tissueremoval device of claim 1, wherein the outer cannula is rotatable aboutthe inner cannula longitudinal axis such that rotation of the outercannula about the inner cannula longitudinal axis with respect to thehandpiece causes the inner cannula to rotate about the inner cannulalongitudinal axis with respect to the handpiece while maintaining afixed circumferential orientation between the outer cannula opening andthe inner cannula.
 11. The tissue removal device of claim 10, whereinthe inner cannula has a radial direction, and when the inner cannula andthe outer cannula are in the fixed circumferential orientation, thehinge is spaced apart from the outer cannula opening in the radialdirection.
 12. The tissue removal device of claim 1, further comprisingan inner sleeve disposed about the outer cannula and a rotation wheelconnected to the inner sleeve and the inner cannula, such that rotationof the rotation wheel causes the outer cannula to rotate about the innercannula longitudinal axis.
 13. The tissue removal device of claim 12,wherein the housing is a lower housing, the handpiece further comprisesan upper housing connected to the lower housing, and the inner sleeve isdisposed in the upper housing.
 14. The tissue removal device of claim13, wherein the rotation wheel is partially disposed in the upperhousing such that a user engagement surface of the rotation wheelprojects away from the upper housing.
 15. The tissue removal device ofclaim 1, wherein an entire portion of the motor is positioned proximalof the housing midpoint along the direction of the housing longitudinalaxis.
 16. The tissue removal device of claim 1, wherein the housinglongitudinal axis is spaced away from the proximal end of the innercannula in a direction perpendicular to the inner cannula longitudinalaxis.